Noticing when getting on / off throttle that it's not smooth with engagement - eg seems like driveline slack....I dont have a wheel stand yet so cant check chain adj....also have a shaft drive GS so maybe I'm sensitive to the differences?

It's not the chain. For reference, the chain slack spec for the Gen 1 Yamaha FZ1 is 1.6" - 1.9". They run along happily with the bottom run of the chain dancing around and between the FZ1 I had and many more, with many hundreds of thousands of miles, there has never been a report of a chain coming off. And anyone who has ridden one of those bikes knows they are smooth as butter.

My SDR was rough at first too. I got it with 3800 miles on it, and it was like that even then. Now it has just shy of 29,000 and everything about it is much smoother.

Patience, young padawan.

btw I went to a 16t front sprocket and like it better than the stock 17t.